双长周期光栅调制的光纤光栅光谱分析及其在智能结构监测中的应用  

Spectral Analysis of Fiber Bragg Grating Modulated by Double Long Period Grating and Its Application in Smart Structure Monitoring

作　　者：芦吉云[1] 梁大开[1] 张晓丽[1] 朱珠[1] 

机构地区：[1]南京航空航天大学,航空科技智能材料与结构重点实验室,江苏南京210016

出　　处：《光谱学与光谱分析》2009年第12期3429-3433,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(60477031);国家自然科学基金重点项目(60535020)资助

摘　　要：提出一种双长周期光栅(LPFG)调制光纤Bragg光栅(FBG)传感器光谱的方法。双LPFG是由两个中心波长一致的LPFG构成,FBG反射光谱位于双LPFG透射光谱的线性范围内。在对FBG及双LPFG光谱分析的基础上,利用双LPFG的带阻滤波特性,获得FBG反射光经双LPFG调制后的出射光谱并进行分析。将FBG粘贴于钢梁表面,当钢梁产生弯曲应变时,FBG光谱的中心波长发生偏移,经双LPFG调制的FBG光谱的峰值随之变化,引起双LPFG出射光强的变化。采用光电探测器监测经双LPFG调制后FBG的输出光强,得滤波后光强与FBG中心波长变化成线性关系,可探测的材料(钢梁)最小应变为1.05με。将该方案应用于光纤智能结构冲击监测中,采用摆锤冲击法对四边固支碳纤维板(CFP)试件进行冲击,利用FBG测量板结构的冲击响应信号,系统采集到的动态信号时域波形及频谱与电涡流位移计的测量结果吻合得很好,实验结果表明采用该调制、解调方案测量结构的冲击响应是可行的。研究结果为FBG在光纤智能结构动态监测领域提供了实验参考。Spectrum of fiber bragg grating（FBG）sensor modulated by double long period grating（LPFG）is proposed in the paper.Double LPFG consists of two LPFGS whose center wavelengths are the same and reflection spectrum of FBG sensor is located in linear range of double LPFG transmission spectrum.Based on spectral analysis of FBG and double LPFG,reflection spectrum of FBG modulated by double LPFG is obtained and studied by use of band-hider filter characteristics for double LPFG.An FBG sensor is attached on the surface of thin steel beam,which is strained by bending,and the center wavelength of FBG sensor will shift.The spectral peak of FBG sensor modulated by double LPFG is changed correspondingly,and the spectral change will lead to variation in exit light intensity from double LPFG.Experiment demonstrates that the relation of filtering light intensity from double LPFG monitored by optical power meter to center wavelength change of FBG sensor is linear and the minimum strain of material（steel beam）detected by the modulation and demodulation system is 1.05 με.This solution is used in impact monitoring of optical fibre smart structure,and FBG sensor is applied for impulse response signal monitoring induced by low-velocity impact,when impact pendulum is loaded to carbon fiber-reinforced plastics（CFP）.The acquired impact response signal and fast Fourier transform of the signal detected by FBG sensor agree with the measurement results of eddy current displacement meter attached to the FBG sensor.From the results,the present method using FBG sensor is found to be effective for monitoring the impact.The research provides a practical reference in dynamic monitoring of optical fiber smart structure field.

关 键 词：光纤BRAGG光栅传感器 长周期光纤光栅 冲击监测 应变 

分 类 号：O433.4[机械工程—光学工程]